This laboratory has provided a number of services to developmental Endocrinology Branch and other NICHD investigators. Sheep anti-rabbit gamma globulin sera (second antibody) was generated, titered and distributed to NICHD Intramural Investigators, mostly in PRB, ERRB and DEB. Rigid quality control and efficient harvesting procedures were combined to provide a high quality reagent at a fraction of the commercial cost. Radioimmunoassay procedures for polypeptide and steroid hormones of reproductive interest have been maintained and utilized for research investigations. Teaching of radioimmunoassay methodology for polypeptide and steroid hormones has been provided as required for branch fellows. In addition, antisera to steroid hormones were provided off-campus investigators.